Hiking poles go in one hand
Hiking poles go in the pack
Climbing shoes go on
Better have a rope because you don't want to downclimb this
Better have a partner because climbing up this might be rough
Better have a partner who can lead this because you can't
Don't know anyone who can climb this

Class 1: A trail so easy you could do it hopping on ONE foot.
Class2: The trail has some undulations so you better use TWO feet.
Class 3: There's no more trail and you might have to use both feet and and a hand to keep going up, or more simply you'll be using THREE limbs.
Class 4: There's big exposure so you better use both hands and both feet, which equals FOUR limbs.
Class 5: Technical climbing with severe fall exposure, use all four limbs plus one rope, or FIVE appendiges for protection.

class I: I went for a hikeclass 2: I went for a hike and it was hard tooclass 3: I went for a hike, it was hard, and I used my handsclass 4: I went for a hike, it was hard, I used my hands, and it was steep tooClass 5: I went for a hike, it was hard, I used my hands, it was steep, and I used a rope

Or sometimes I just use hiking or scrambling or climbing. These three are easier concepts to teach than the full soup of III 5.9 A1 M6 or some such, which imply more precision than really exists. Also the grades are subjective and situational. Some particular climb (the third flatiron comes to mind) might compel one person to use a rope (making it a class 5 for him), while someone else might cruise it in flip flops (making it a class 3 for them). Same thing if the weather intervenes, changing your scramble into a mixed climb. I also sometimes use things like 5.easy, 5.hard, 3.10, etc.